Recently, AI writing assistance tools have emerged as pivotal aids in addressing L2 learners' writing challenges. With this emergence, this qualitative study delves into the perceptions of Thai EFL learners regarding the utilization of AI writing assistance tools. A total of ten Thai non-English-major undergraduates were interviewed to explore their experiences. The results unveiled a nuanced perspective, wherein the participants acknowledged both benefits and challenges linked to the integration of AI writing assistance tools in their writing processes. In terms of benefits, the participants highlighted improvements in linguistic aspects, enhanced affective factors, and pragmatic advantages. Despite these perceived benefits, the participants were attuned to the trade-offs associated with these tools, encompassing concerns about over-reliance on technology, the potential for academic misconduct, and the occasional ineffectiveness of the tools. This study provides valuable insights into the multifaceted impact of AI writing assistance tools on Thai EFL learners, offering implications for pedagogy and future research in the realm of language learning technology.